In order to block users from accessing the Untangle device by IP address in a browser, we can specify which host addresses, or entire subnets, will be able to access the device. By going to Admin configuration from Config > Administration > Admin, we can set restricted Administration access per subnet. In this field, we can choose a single host address, an entire subnet, or multiple subnets by separating the networks with a comma.
IMPORTANT: Make sure you include a subnet mask when configuring by entire subnet.
When a user attempts to login from an IP address that is not listed, they will receive a blocked screen.